/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.jdbc;

import static org.apache.hadoop.test.GenericTestUtils.waitFor;
import static org.apache.phoenix.jdbc.HighAvailabilityGroup.PHOENIX_HA_GROUP_ATTR;
import static org.apache.phoenix.jdbc.HighAvailabilityPolicy.PARALLEL;
import static org.apache.phoenix.jdbc.HighAvailabilityTestingUtility.HBaseTestingUtilityPair;
import static org.apache.phoenix.jdbc.HighAvailabilityTestingUtility.doTestBasicOperationsWithConnection;
import static org.junit.Assert.assertTrue;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.function.Supplier;
import org.apache.phoenix.end2end.NeedsOwnMiniClusterTest;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Category(NeedsOwnMiniClusterTest.class)
public class ParallelPhoenixConnectionFallbackIT {

  private static final Logger LOG =
    LoggerFactory.getLogger(ParallelPhoenixConnectionFallbackIT.class);
  private static final HBaseTestingUtilityPair CLUSTERS = new HBaseTestingUtilityPair();
  private static final Properties PROPERTIES = new Properties();

  private static String jdbcUrl;
  private static HighAvailabilityGroup haGroup;
  private static String tableName = ParallelPhoenixConnectionFallbackIT.class.getSimpleName();
  private static String haGroupName;

  @BeforeClass
  public static void setUpBeforeClass() throws Exception {
    haGroupName = ParallelPhoenixConnectionFallbackIT.class.getSimpleName();
    CLUSTERS.start();
    DriverManager.registerDriver(PhoenixDriver.INSTANCE);
    PROPERTIES.setProperty(PHOENIX_HA_GROUP_ATTR, haGroupName);
    PROPERTIES.setProperty(PhoenixHAExecutorServiceProvider.HA_MAX_POOL_SIZE, "1");
    PROPERTIES.setProperty(PhoenixHAExecutorServiceProvider.HA_MAX_QUEUE_SIZE, "2");
    PROPERTIES.setProperty(PhoenixHAExecutorServiceProvider.HA_THREADPOOL_QUEUE_BACKOFF_THRESHOLD,
      "0.5");

    // Make first cluster ACTIVE
    CLUSTERS.initClusterRole(haGroupName, PARALLEL);

    jdbcUrl = CLUSTERS.getJdbcHAUrl();
    haGroup = HighAvailabilityTestingUtility.getHighAvailibilityGroup(jdbcUrl, PROPERTIES);
    LOG.info("Initialized haGroup {} with URL {}", haGroup.getGroupInfo().getName(), jdbcUrl);
    CLUSTERS.createTableOnClusterPair(haGroup, tableName);
  }

  @AfterClass
  public static void tearDownAfterClass() throws Exception {
    DriverManager.deregisterDriver(PhoenixDriver.INSTANCE);
    CLUSTERS.close();
  }

  @Test
  public void testParallelConnectionBackoff() throws Exception {
    Connection connA = DriverManager.getConnection(jdbcUrl, PROPERTIES);
    assertTrue(connA instanceof ParallelPhoenixConnection);
    doTestBasicOperationsWithConnection(connA, tableName, haGroupName);
    // Block threads of the pool
    CountDownLatch cdl1 = new CountDownLatch(1);
    CountDownLatch cdl2 = new CountDownLatch(1);
    ParallelPhoenixContext contextA = ((ParallelPhoenixConnection) connA).getContext();
    waitFor(() -> contextA.getChainOnConn1().isDone(), 100, 5000);
    waitFor(() -> contextA.getChainOnConn2().isDone(), 100, 5000);
    contextA.chainOnConn1(getSuplierWithLatch(cdl1));
    contextA.chainOnConn2(getSuplierWithLatch(cdl2));
    waitFor(() -> PhoenixHAExecutorServiceProvider.hasCapacity(PROPERTIES).get(0)
      && PhoenixHAExecutorServiceProvider.hasCapacity(PROPERTIES).get(1), 100, 5000);
    ExecutorService executor = Executors.newFixedThreadPool(1);
    // Since both the cluster executors are busy, the new connection will be
    // put in the executor queue, and a connection won't be returned unless
    // this is picked. At this point of time, the capacity is available, so
    // this should be a ParallelPhoenixConnection.
    Future<Connection> futureConnB =
      executor.submit(() -> DriverManager.getConnection(jdbcUrl, PROPERTIES));

    // The previous call of connection creation should fill the queue by half.
    waitFor(() -> !PhoenixHAExecutorServiceProvider.hasCapacity(PROPERTIES).get(0)
      && !PhoenixHAExecutorServiceProvider.hasCapacity(PROPERTIES).get(1), 100, 5000);

    // This should be backed off now, as the capacity is not available.
    Connection connC = DriverManager.getConnection(jdbcUrl, PROPERTIES);
    // We should've backed off now since creating the prev connection should fill
    // the queue half
    assertTrue(connC instanceof PhoenixConnection);
    // Let the threads go
    cdl1.countDown();
    cdl2.countDown();

    // Once the previous tasks are done, we expect the futureConnB to be picked and be done.
    waitFor(() -> futureConnB.isDone(), 1000, 5000);
    Connection connB = futureConnB.get();
    assertTrue(connB instanceof ParallelPhoenixConnection);

    doTestBasicOperationsWithConnection(connB, tableName, haGroupName);
    ParallelPhoenixContext contextB = ((ParallelPhoenixConnection) connB).getContext();
    waitFor(() -> contextB.getChainOnConn1().isDone(), 100, 5000);
    waitFor(() -> contextB.getChainOnConn2().isDone(), 100, 5000);

    // Now that the queue has capacity, this should be ParallelLPhoenixConnection.
    Connection connD = DriverManager.getConnection(jdbcUrl, PROPERTIES);
    assertTrue(connD instanceof ParallelPhoenixConnection);
    closeConnections(connA, connB, connC, connD);
  }

  private Supplier<?> getSuplierWithLatch(CountDownLatch cdl) {
    Supplier<?> s = () -> {
      try {
        cdl.await();
      } catch (InterruptedException e) {
        throw new RuntimeException(e);
      }
      return null;
    };
    return s;
  }

  private void closeConnections(Connection... connections) {
    for (Connection conn : connections) {
      try {
        conn.close();
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
  }
}
